I've just set up a Linux gateway as a tunnel endpoint and while the routed /64 works fine, I can't seem to get the routed /48 to work.
My routed /64 is 2001:470:1f15:dc0::/64. I can reach ipv6.google.com from a PC in this network.
My routed /48 is 2001:470:d42a::/48. I've created a /64 subnet, 2001:470:d42a:1::/64, and added 2001:470:d42a:1::1 to the inside interface on the router. Ping or traceroute does not work if I specify an address in this net as the source address:
router:~# traceroute -s 2001:470:d42a:1::1 ipv6.google.com
traceroute to ipv6.google.com (2a00:1450:8003::6a), 30 hops max, 40 byte packets
1 * * *
2 * * *
3 * * *
[...snip...]
30 * * *
If I specify the address in the /64 network as the source address, everything works:
router:~# traceroute -s 2001:470:1f15:dc0::1 ipv6.google.com
traceroute to ipv6.google.com (2a00:1450:8003::6a), 30 hops max, 40 byte packets
1 rcastell-1.tunnel.tserv11.ams1.ipv6.he.net (2001:470:1f14:dc0::1) 43.526 ms 43.279 ms 43.083 ms
2 gige-g2-20.core1.ams1.he.net (2001:470:0:7d::1) 43.322 ms 43.529 ms 43.542 ms
3 pr61.ams04.net.google.com (2001:7f8:1::a501:5169:1) 72.027 ms 43.524 ms 43.589 ms
4 2001:4860::1:0:8 (2001:4860::1:0:

44.347 ms 44.361 ms 44.382 ms
5 2001:4860::1:0:2a (2001:4860::1:0:2a) 48.165 ms 47.947 ms 47.770 ms
6 2001:4860::34 (2001:4860::34) 47.142 ms 2001:4860::35 (2001:4860::35) 42.476 ms 2001:4860::34 (2001:4860::34) 41.740 ms
7 2001:4860:0:1::2b (2001:4860:0:1::2b) 51.277 ms 51.085 ms 48.966 ms
8 2a00:1450:8003::6a (2a00:1450:8003::6a) 42.775 ms 42.090 ms 42.884 ms
I this a routing issue at HE, or am I missing something here?